Pressure-sensitive adhesive (PSA) tapes are virtually ubiquitous in the home and workplace. In one of its simplest configurations, a pressure-sensitive tape includes a backing layer and an adhesive layer attached to the backing layer. According to the Pressure-Sensitive Tape Council, pressure-sensitive adhesives are known to possess properties including the following: (1) aggressive and permanent tack, (2) adherence with no more than finger pressure, (3) sufficient ability to hold onto an adherend, and (4) sufficient cohesive strength to be removed cleanly from the adherend. Materials that have been found to function well as PSAs include polymers designed and formulated to exhibit the requisite viscoelastic properties resulting in a desired balance of tack, peel adhesion, and shear holding power. PSAs are characterized by being normally tacky at room temperature (e.g., about 20° C. to 25° C.). Materials that are merely sticky or that adhere to a surface do not necessarily constitute a PSA; the term PSA encompasses materials with additional viscoelastic properties.
Acrylic-based pressure-sensitive adhesives have been widely used. These pressure-sensitive adhesive compositions can be prepared with or without an organic solvent. PSA compositions containing organic solvents, while currently dominant in the marketplace, are decreasing in importance due to various issues such as pollution, high energy consumption, and flammability associated with the use of organic solvents. That is, the adhesive industry is increasingly focused on adhesive compositions that have either low or no organic solvent content.
Some such adhesive compositions can, for example, be prepared from water-based latex compositions formed by emulsion polymerization. Such adhesives are described, for example, in U.S. Pat. No. 5,686,518 (Fontenot et al.), U.S. Pat. No. 6,710,128 (Helmer et al.), U.S. Pat. No. 6,511,744 (Centner et al.), U.S. Pat. No. 6,048,611 (Lu et al.), U.S. Pat. No. 4,912,169 (Whitmire et al.), U.S. Pat. No. 6,657,011 (Lau et al.), U.S. Pat. No. 8,258,240 (Suzuki et al.), and U.S. Patent Application Publication No. 2010/0081764 (Ouzineb et al.).